Stihl Fs 450 K Manual
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30 English / USA FS 300, FS 350, FS 400, FS 450, FS 480 If the engine still does not start: :Move the slide control to 0 c :Pull off the spark plug boot (5). :Unscrew and dry off the spark plug. :Open the throttle wide. :Crank the engine several times with the starter to clear the combustion chamber. :Refit the spark plug. Connect the spark plug boot (press it down firmly). :Move the slide control to START. :Set the choke knob to e – even if the engine is cold. :Now start the engine.Throttle cable :Check adjustment of the throttle cable – see Adjusting the Throttle Cable. Tank run until dry and then refueled :Press the fuel pump bulb at least five times – even if bulb is filled with fuel.During break-in period A factory new machine should not be run at high revs (full throttle off load) for the first three tank fillings. This avoids unnecessary high loads during the break-in period. As all moving parts have to bed in during the break-in period, the frictional resistances in the engine are greater during this period. The engine develops its maximum power after about 5 to 15 tank fillings. During operation After a long period of full-throttle operation, allow engine to run for a while at idle speed so that the heat in the engine can be dissipated by flow of cooling air. This protects engine- mounted components (ignition, carburetor) from thermal overload. After finishing work Wait for engine to cool down. Drain the fuel tank. Store the machine in a dry place. Check tightness of nuts and screws (not adjusting screws) at regular intervals and retighten as necessary. 271BA019 KN 5 Operating Instructions
31 FS 300, FS 350, FS 400, FS 450, FS 480English / USA Dirty air filters reduce engine power, increase fuel consumption and make starting more difficult. If there is a noticeable loss of engine power :Turn the choke knob to g :Press in the tab (1). :Pull off the filter cover (2). :Clean away loose dirt from inside the filter cover and around the filter.:Remove the filter element (3) and inspect it – replace if dirty or damaged. :Fit the air filter in the cover. :Push the filter cover into position. Dirty air filters reduce engine power, increase fuel consumption and make starting more difficult. If there is a noticeable loss of engine power :Turn the choke knob to g :Loosen the mounting screw (1). :Pull off the filter cover (2). :Clean away loose dirt from inside the filter cover and around the filter. :Remove the filter element (3) and inspect it – replace if dirty or damaged. :Fit the air filter in the cover. :Fit the filter cover. Cleaning the Air FilterFS 300, 350 1 2 3 250BA022 KN Cleaning the Air FilterFS 400, 450, 480 1 23 256BA074 KN
32 English / USA FS 300, FS 350, FS 400, FS 450, FS 480 Exhaust emissions are controlled by the design of the fundamental engine parameters and components (e.g. carburation, ignition, timing and valve or port timing) without the addition of any major hardware. General InformationThe carburetor comes from the factory with a standard setting. This setting provides an optimum fuel-air mixture under most operating conditions. With this carburetor it is only possible to adjust the high speed screw within fine limits.Standard Setting:Shut off the engine. :Mount approved cutting tool. :Check the air filter and replace if necessary. :Check adjustment of the throttle cable and readjust if necessary – see Adjusting the Throttle Cable.:Turn high speed screw (H) counterclockwise (max. 3/4 turn) as far as stop. :Carefully screw the low speed screw (L) down onto its seat. Then open it one turn counterclockwise. :Start the engine and run it until it is warm. :Adjust idle speed with the idle speed screw (LA) so that the cutting tool does not rotate. Motor Management Adjusting the Carburetor 255BA001 KN LA 1L H 3/4
33 FS 300, FS 350, FS 400, FS 450, FS 480English / USA Adjusting Idle SpeedEngine stops while idling :Carry out standard setting with the low speed screw (L). :Turn the idle speed screw (LA) clockwise until the engine runs smoothly – the cutting tool must not rotate. Cutting tool rotates when engine is idling :Turn the idle speed screw (LA) counterclockwise until the cutting tool stops rotating – then turn the screw about another half to one full turn in the same direction from that position.Erratic idling behavior, poor acceleration :Carry out standard setting with the low speed screw (L). Idle setting too lean: :Turn low speed screw (L) counterclockwise until the engine runs and accelerates smoothly. It is usually necessary to change the setting of the idle speed screw (LA) after every correction to the low speed screw (L). Fine tuning the carburetor for operation at high altitude A slight correction may be necessary if the engine does not run satisfactorily: :Check standard setting. :Warm up the engine. :Turn the high speed screw (H) clockwise (leaner).Mount the Intake Air Preheating kit 4128 007 1001* to prevent the air filter and carburetor icing up at temperatures below +10°C/ +50°F and in powdery or drifting snow. :Remove the standard air filter (1). :Install the special filter (2) for winter operation. :Push cover (3) up against the underside of the filter cover. This is the winter position (upper illustration). * see Guide to Using this Manual Winter OperationFS 400, 450, 480 256BA047 KN 3 1 2 256BA048 KN 1 2 3
34 English / USA FS 300, FS 350, FS 400, FS 450, FS 480 At the end of the cold season: :Remove the special air filter (2) for winter operation and install the standard filter (1) in its place. :Push the cover (3) into the summer position (lower illustration). Switching on handle heating (special option) :Move the switch in the left handle to Z – move the switch back to O to turn off the heating. If the handle temperature feels too high – move switch to O. There is no risk of overheating during long periods of operation. The heating system is maintenance-free. Contact your servicing dealer if you have any problems.Wrong fuel mix (too much engine oil in the gasoline), a dirty air filter and unfavorable running conditions (mostly at part throttle etc.) affect the condition of the spark plug. These factors cause deposits to form on the insulator nose which may result in trouble in operation. Electric Handle Heating 256BA076 KN Checking the Spark Plug 000BA002 KN
35 FS 300, FS 350, FS 400, FS 450, FS 480English / USA If engine is down on power, difficult to start or runs poorly at idling speed, first check the spark plug. :Remove spark plug – see Starting / Stopping the Engine. :Clean dirty spark plug. :Check electrode gap (A) and readjust if necessary – see Specifications. :Use only resistor type spark plugs of the approved range. Rectify problems which have caused fouling of spark plug: :Too much oil in fuel mix. :Dirty air filter. :Unfavorable running conditions, e.g. operating at part load. Fit a new spark plug after approx. 100 operating hours or earlier if the electrodes are badly eroded.To reduce the risk of fire and burn injury, use only spark plugs authorized by STIHL. Always press spark plug boot (2) snugly onto spark plug terminal (1) of the proper size. (Note: If terminal has detachable SAE adapter nut, it must be attached.) A loose connection between spark plug boot and ignition wire connector in the boot may create arcing that could ignite combustible fumes and cause a fire.If engine running behavior is unsatisfactory even though the air filter is clean and the carburetor and throttle cable are properly adjusted, the cause may be in the muffler. Have your STIHL dealer inspect the muffler for carbonization. STIHL recommends that maintenance and repair work be carried out only by authorized STIHL dealers. 000BA036 TR 1 Engine Running Behavior
36 English / USA FS 300, FS 350, FS 400, FS 450, FS 480 Use STIHL gear lubricant for brushcutters (see Guide to Using this Manual). :Check grease level about every 100 hours of operation. :Unscrew the filler plug (1). :If no grease can be seen on the inside of the filler plug, screw the tube of lubricant (2) into the filler hole. :Squeeze grease into the gear housing – till 1/5 oz (5 g). Do not completely fill the gear housing with grease. :Refit the filler plug and tighten it down firmly. Replacing the starter rope The rewind spring may pop out and uncoil – take care to avoid injury during the following operation. :Remove the screws (1). :Lift away the fan housing. :Remove the spring clip (2). :Carefully pull off the rope rotor with washer (3) and pawl (4).:Ease the cap (5) out of the starter grip. :Remove remaining rope from the rotor and grip. :Tie a simple overhand knot in the end of the new starter rope (see Specifications) and then thread the rope through the top of the grip and the rope bush (6). :Refit the cap in the grip. Lubricating the Gearbox 12 256BA044 KN Replacing the Starter Rope and Rewind Spring 1 1 11 256BA063 KN 3 24 256BA032 KN 6 5 256BA033 KN
37 FS 300, FS 350, FS 400, FS 450, FS 480English / USA :Thread the rope through the rotor and secure it in the rotor with a simple overhand knot. :Lubricate the rope rotor bearing bore with non-resinous oil (Special Accessories). :Slide rotor onto starter post – turn it back and forthe until the loop of the rewind spring engages. :Fit the pawl (4) and washer (3), and press the spring clip (2) into position. The spring clip must point counter- clockwise and engage the peg on the pawl. Tensioning the Rewind Spring:Make a loop in the unwound starter rope and use it to turn the rope rotor six full revolutions in the direction of the arrow (see illustration). :Hold the rotor steady – straighten the twisted rope. :Seilrolle loslassen :Release the rotor and let go of rope slowly so that it winds onto the rotor. The starter grip must sit firmly in the rope guide bush. If the grip droops to one side: Increase spring tension by one additional turn. When the starter rope is fully extended it must be possible to rotate the rotor at least another half turn (FS 300, 350) or one and a half turns (FS 400, 450, 480)).If this is not possible, the spring is overtensioned and could break. :Take one turn of the rope off the rotor. :Fit the fan housing. Replacing the Rewind Spring Broken parts of the spring may still be under tension and could be thrown in your direction when you pull off the rope rotor and remove the spring housing. To reduce the rist of injury, wear eye and face protection and work gloves for the following operations: :Remove the rope rotor as described in Replacing the Starter Rope. FS 400, 450, 480) :Remove screw from the outer spring loop. :Remove parts of old spring. :Lubricate the new spring with a few drops of non-resinous oil (Special Accessories). 256BA034 KN 3 24 256BA032 KN 427BA016 KN
38 English / USA FS 300, FS 350, FS 400, FS 450, FS 480 :Place spring with frame in position – check that outer spring loop (8) is correctly seated. :Use a suitable tool to push the spring into the housing. Apply tool through the openings (see arrows). The frame slips off in this process. If the spring pops out and uncoils during installation: Refit it in the spring housing in the counterclockwise direction – start outside and work inward. :Fit the screw. :Install the rope rotor as described in Replacing the Starter Rope. :Tension the rewind spring. :Fit the fan housing.FS 300, 350 :Take out the screws (9). :Remove the spring housing and parts of old spring. :Lubricate the new spring spring in the new spring housing with a few drops of non-resinous oil (Special Accessories). :Fit new spring with spring housing – bottom plate must face up. If the spring pops out and uncoils during installation: Refit it in the spring housing in the clockwise direction – start outside and work inward. :Fit the screws. :Install the rope rotor as described in Replacing the Starter Rope. :Tension the rewind spring. :Fit the fan housing.For periods of about 3 months or longer :Drain and clean the fuel tank in a well ventilated area. :Dispose fuel properly in accordance with local environmental requirements. :Run engine until carburetor is dry – this helps prevent carburetor diaphragms sticking together. :Remove, clean and inspect the cutting tool. :Thoroughly clean the machine – pay special attention to the cylinder fins and air filter. :Store the machine in a dry, high or locked location – out of the reach of children and other unauthorized persons. 8 271BA038 KN 99 271BA039 KN Storing the Machine
39 FS 300, FS 350, FS 400, FS 450, FS 480English / USA Never attempt to straighten or weld a bent or cracked cutting tool – it might shatter and cause serious or fatal injury. :Resharpen frequently, take away as little material as possible – two or three strokes of the file are usually enough. To avoid out-of-balance: :Resharpen the cutters (1) uniformly – do not alter the contour of the parent blade (2) in any way. :After resharpening about 5 times, have blade checked on STIHL balancer*. Grass Cutting Blades, Brush KnifeUse a flat file* to sharpen dull cutting grass cutting blades. In case of more serious wear or nicks: Resharpen with a grinder or have work done by STIHL dealer. Chisel Tooth Circular Saw Blades Sharpen as described in the instructions supplied or printed on the inside of the blades packaging.Scratcher Tooth Circular Saw BladesUse a flat file to file the backs of the teeth until the tips of the teeth are restored to full sharpness. * see Guide to Using this Manual Sharpening Metal Cutting Tools 2 2 12 1 1 002BA042 KN